Sunday, February 13

Myths About "Safety in Numbers"

Safety in Numbers and the theory behind it is what kicked this series off. A week ago, the Minneapolis Star Tribune headline read: "As Bicycle Use Climbs, Rate of Crashes With Vehicles Falls." I've seen headlines like this often enough, but THE NEXT DAY, The New York Times claimed "Data Confirm What Cyclists Knew: San Francisco Streets Are Hazardous" where they state that cyclists are getting clipped at an ever-faster rate. Earlier, the Atlanta Journal Constitution bemoaned new cyclists filling the hospitals. Puzzled, I went to "The Atlantic" that claims cycling is increasing everywhere. As I researched even further, even the League of American Bicyclists was trumpeting the "Safety in Numbers" effect in its blog. The whole "safety in numbers" theory ties back to a paper written by Peter Jacobsen, which may be found here. While John Forester pointed out problems in the methods, and even I made a post on Cycle*Dallas to suggest people shouldn't get too enthusiastic about the whole notion, THIS POST is about the unexamined MYTH BEHIND THE MYTH ABOUT WHY "Safety in Numbers" might have validity.

You see, two paragraphs in the Minneapolis article stood out:

Why is this happening? Familiarity breeds safety, one city bike advocate believes. "People are so used to seeing bicyclists -- love them or hate -- and they don't want to hit them," said Shaun Murphy, coordinator of the city's nonmotorized transportation program. Murphy said the map of hot spots for bike-car accidents doesn't show major issues around the University of Minnesota because drivers there are so used to watching for bikes.

Do bike lanes help? Murphy also credits more bike lanes. Bike lanes can benefit pedestrians as well. When bike lanes were striped on Riverside Avenue, for example, the number of bikers riding on sidewalks dropped by 87 percent, said Hilary Reeves, a spokeswoman at Transit for Livable Communities, which manages a federal grant to promote biking and walking in the Twin Cities.

So, if I'm to believe the article (remember - most crashes are simple falls and don't involve motor vehicles at all), it turns out that if there are more bicyclists, motorists no longer want to run into them because they simply get used to seeing them. Think about THAT for a moment. Motorists don't actually actively try not to run into anything as they were all taught from the time they first entered driver's ed, but they suddenly get used to cyclists and no longer want to hit them. Kumbaya. Motorists don't hit a cyclist because that cyclists was riding against traffic in the dark with no lights or reflector; the motorist hit the cyclist because "they weren't used to watching for bikes." Forgive me if I'm a little dubious about this. All but a rare lunatic fringe of psycopaths recognize that hitting a cyclist is not a good thing and hitting one is likely to prompt awkward insurance questions if nothing else.

I suppose this popular theory about why there is safety in numbers is possible, but where I live, there really are NOT a lot of cyclists, but the motorists still avoid hitting any cyclist they see and recognize, whether or NOT they are USED to seeing them. THE NOTION THAT MOTORISTS NO LONGER HIT CYCLISTS SIMPLY DUE TO A CHANGE WITHIN EACH MOTORIST AS CYCLIST NUMBERS INCREASE IS THE REAL MYTH.

Let's assume that there IS validity to the safety in numbers theory and examine why added numbers might make things safer. The popular hypothesis is that motorists simply get better at not hitting cyclists somehow. HOWEVER, THERE ARE LOTS OF OTHER REASONS THIS MIGHT BE SO. For example, embedded in the second paragraph is one reason - a drop of 87% in bikers riding on sidewalks would certainly reduce crash rates. As another alternate hypothesis, it seems LIKELY that traffic engineers consider design elements for cyclists MORE when there are more cyclists and that THIS might also explain a drop in crash rates. Certainly, traffic engineers are quick to take credit for their efforts when auto crash rates drop. I would put this as the "when cyclists are more numerous, traffic engineers stop putting them in extreme danger as often" theory. In truth, there is probably more evidence in support of this second theory than the one that motorists suddenly get mellow and attentive. Another theory is that more cyclists leads to more cyclists seeing cyclists riding sensibly and so they get better quicker simply by "monkey see monkey do." Even THIS theory seems more likely than the "kinder gentler motorist" one.

The problem is that we don't really KNOW very well what causes collision rates to drop. All we really know for sure is that riding safer is safer. The reason is that there is little recent research done involving cyclists that isn't fatally tainted with political agendas and a desire to substantiate predetermined results. While it is easy to blame or credit motorists for crash rate changes, it is MORE LIKELY that these changes are due to changes in the way that roads are designed, and the way that cyclists use those roads.

Oh, and that graph at the top of the page? The "accident rates" were generated by a random number generator in Excel. No cyclists were harmed in its production.

In the words of John Schubert, when he rightly took me to task on the subject:

"I ride where I’m seen. The human being driving the Hummer sees me, whether I’m alone or not, on Fifth Avenue or Podunk Street. He doesn’t want a collision, so he avoids the collision. What could be simpler?"

MONDAY UPDATE: WARNING - MATH AHEAD!
Well, I started crunching some numbers from the Jacobsen paper, but along the way I found some interesting anomalies that are slowing things down. First off, I think that even the most enthusiastic proponent of the "more watchful motorist" theory will concede that watchfulness is not all that's going on. For example, I found that according to the NHTSA, alcohol was involved in 38% of all car-bike cyclist fatalities in 2008 and I'm torn about how to remove clear cases where watchfulness is a non factor from the mix. What is more perplexing is that, according to the Jacobsen paper itself, sometimes it appears to get MORE dangerous for each cyclist when there are more cyclists out. In the UK, between 1984 and 1999, a doubling of cyclists would have resulted in nearly THREE TIMES as many cycling fatalities. I'll have to ponder that number a little. If we're to accept the "motorists are changing" theory, in the UK, it bodes poorly for cyclists if more ride. Regardless of anything else, I hope we can all agree that making it easier for motorists to notice us and what we are planning to do next is a sound policy. That is as true for a clueless motorist on a cell phone as for one that's almost paralyzed from fear he/she might hit a cyclist. While a motorist might well be looking for a cyclist darting off a sidewalk against traffic in the dark, any motorist being so watchful is going above and beyond the call of duty, and any cyclist that counts on such a response from a motorist is likely to fare poorly. Even in Holland.

25 comments:

cliff said...

I keep hearing accident RATES and not numbers.
If an area has a handful of bad drivers then the
more cyclists the less chance any ONE cyclist
will be a victim.

Steve A said...

What is a more effective means to reduce crash rates? A - depend on added cyclists to somehow mask the effects of those bad drivers or B - have those added cyclists demand that the cops hold the bad drivers accountable? That second approach supports the theory that government response may be playing a larger role than is recognized.

I don't think Cliff subscribes to the "cuddly motorist" theory any more than I do.

John Romeo Alpha said...

The SIN concept is similar to WWII Atlantic shipping convoy strategy. This strategy was not designed with the lives or mental well-being of merchant seamen foremost, it was intended to benefit the shippers and receivers on either end. Maybe if cyclists had air cover it would be more relevant to us.

Steve A said...

There is ONE essential difference, as Schubert pointed out. Motorists are NOT trying to hit cyclists or anything else in the roadway. IN WWII, the U boats were TRYING to hit ships. That is a difference that changes EVERYTHING when it comes to the notion of SIN.

If it were otherwise, we'd not see the fascination with High Vis that is fashionable nowadays. Instead, cyclists would be wearing camo, getting concealed carry permits and, dare I say it, wearing sniper gloves.

John Romeo Alpha said...

Hmm. Me: SIN was relevant for Merchant convoys but not for cyclists. You: Cyclists are not merchant convoys. Me: ???

Steve A said...

I misinterpreted JRA's sense. Upon reading it again, it MAKES good sense. OTOH, some group rides do look a bit like convoys.

Khal said...

Convoys were designed to maximize the coverage of merchant ships by a limited number of escorts and fellow merchant ships. Not a lot different from B-17 formations. Yeah, a lot of them got shot down or sunk. The idea was that you got the goods delivered. You knew people were going to die. Jon is right, it was about delivering goods, not about not getting killed. But if everyone got killed, no goods delivered. So the two had to work. But face it, we built Liberty Ships like gangbusters knowing a lot were going to be decorating the bottom of the Atlantic Ocean.

If a submarine was sighted, it could be attacked. Convoys were in turn attacked by massed U-Boats, i.e., wolfpacks.

But I see no logical comparison here. Wolfpacks of motorists are not out there trying to kill cyclists. In spite of the agit-prop out there.

What we have instead are inexperienced riders, lousy riders, bad facilities, and often distracted motorists. If SIN does anything, it does provide motorists the expectation of interacting with cyclists. It doesn't make lousy facilities safe. Safety in numbers doesn't protect the dumb-sh*it cyclist riding at night without lights, swimming salmon into intersections, nor does it protect a cyclist from a guy texting on his blackberry.

Steve has it nailed. One has to look for causation and test hypotheses against real variables, not against religious myths.

John said...

I don't think anyone is suggesting that motorists currently want to hit cyclists. They just suck at noticing cyclists. So more cyclists doesn't make motorists kinder or nicer, but it does make them better at paying attention.

Scott said...

I was just thinking what John said.

The Safety in Numbers theory is not entirely a myth. How many times have we heard of drivers "not seeing" cyclists, even highly visible ones? By encountering so many more cars than bikes, their brains are programmed to look for cars, not bikes.

More cyclists on the road being seen by motorists increases motorists' awareness of the presence of cyclists, creating Safety in Numbers.

Keri said...

I'm used to watching for ninjas in my neighborhood because there are a lot of them. I suspect they've achieved some sort of safety in numbers by making us all drive (whatever we drive) on high alert to scan for swooshing black forms in the night.

That produces an equivalent effect we could call Resentment in Numbers: the price of SIN.

Steve A said...

I sense a math moment update to this post! In it, I will assume the Jacobsen paper is NOT flawed. Even then, it appears that the watchful motorist theory is questionable and Jacobsen did not attempt to prove motorist behavior explained his phenomena. He merely suggested it might be a cause.

Anonymous said...

Cuddly drivers: myth. Injury RATE dropping due to bicycle facilities and/or increased cyclists: very well may not be a myth. Pedestrian injuries and road injuries have been shown to increase non-linearly with volume. Why not bikes? As someone pointed out earlier, the presence of increased cyclists could increase awareness amongst drivers. They will be more attentive when they bang a right turn if they know there is a high number of cyclists traveling with them. Seems reasonable.

Admittedly, the gentleman you quoted may have worded his statement a little poorly.


And Keri, is RIN really what we want to cater to here? GOOD. Please continue to drive on high alert. You're controlling 2 tons of metal.

Anonymous said...

Following up on my comment addressing Keri, I'm not saying that cyclists can run amuck and the onus is on the drivers to watch out for them. Often times I feel like the complaints from drivers about reckless cyclists are exaggerated, but cyclists need to follow safe practices, and better education is necessary. Put bike classes in elementary gym class!

Khal said...

Resentment in Numbers is countered by bicyclists transitioning to safer behavior as they become more numerous, i.e., Transitioning in Numbers. This is followed by greater transparency in bicyclist-motorist interaction since both bicyclists and motorists will be more predictable and aware of each other. Hence safety in numbers follows.

So called RIN TIN TIN SIN effect.

Khal said...

Anon, I once worked on a team of advocates who wrote a grant proposal to have bike ed taught in all fourth grades in Hawaii. We had the Hawaii Dept. of Education testify AGAINST us in the Hawaii Legislature.

They said it would detract from instructional time. This was the same HI-DOE that was reducing phys ed and putting more junk food vending machines in the schools (back in the 1990's) and then complaining that the kids were hyperactive and couldn't learn. The common answer? Put 'em on Ritalin.

Go figure.

Steve A said...

I almost had an encounter with a cyclist today. I was riding on the 183 Freeway Service Road when I came across a cyclist riding the wrong way toward me. After we both waved nicely, I shouted "you're going the wrong way!" He passed about 8 feet to my right, which was closer than I really felt comfortable with.

If cyclists become more numerous around here, the cops won't put up with such bull manure any more, so we really WILL all be safer.

Khal said...

"...While a motorist might well be looking for a cyclist darting off a sidewalk against traffic in the dark, any motorist being so watchful is going above and beyond the call of duty.."

Having dodged more than a few of our Darwin Award contestants over the years, do we really have to be constantly saving them from themselves?

To some degree, this discussion reminds me of the health care debate. I don't have a problem with public health programs, but I get a little tired of doling out my tax dollars to people who obviously care so little about their own health but are happy to have me pay for the results of their excesses.

Tom said...

"Motorists don't actually actively try not to run into anything as they were all taught from the time they first entered driver's ed, but they suddenly get used to cyclists and no longer want to hit them."

I think that you are grossly misrepresenting the article which you quote. Shawn Murphy is not saying that motorists enjoy hitting cyclists but seeing more of them on the street cures them of this psychopathic affliction. He directly says that no one wants to hit cyclists, regardless of whether or not they think cycling is a good thing. He is implying that the very presence of more cyclists makes them more noticeable and will train drivers to be expect them. For instance, where a driver might have just hooked a right turn, he or she may check for a cyclist in his or her blind spot. Murphy says "people are so used to seeing bikes...AND they don't want to hit them", NOT "people are so used to seeing bikes THAT they don't want to hit them". YOU, Steve, were the one who extended his statement to the example of the cyclist at night without lights on. Who is actually insisting that motorists watch for cyclists without lights going the wrong way? I think any reasonable person can agree fault can be assumed to either the cyclist or the driver, but the driver must be constantly vigilant in an area with pedestrians and cyclists. In addition, bicycle infrastructure may help them be more vigilant.


"While a motorist might well be looking for a cyclist darting off a sidewalk against traffic in the dark, any motorist being so watchful is going above and beyond the call of duty, and any cyclist that counts on such a response from a motorist is likely to fare poorly."

Such wording muddies the argument, because you haven't quoted anyone who is coming remotely close to saying that drivers are responsible for looking out for cyclists behaving poorly.

Now, I don't necessarily disagree with your point that safety increases not because of a behavioral change in each motorist. I think it may have some effect, but I don't look at it as a training of motorists. I view it in the same way that I think the built environment provides cues to drivers. Driving a car through a busy parking lot puts drivers on their toes as they yield to pedestrians and other cars. Driving you car next to a bike lane puts drivers on their toes as they realize they may have to yield to a cyclists if they wish to turn right.

Steve A said...

Certainly I exaggerated. I hope it was clear I was doing so. However, when you add together all the accident causes in which added motorist watchfulness might explain reduced collisions, they do not explain the effect and they CERTAINLY don't explain the UK data. That being the case, I'd certainly put motorist behavior changes into the suspect category when the very same news article also touts an 87% reduction in sidewalk riding due to causes entirely unrelated to motorist caution. Saying "we don't know why" is a first step to finding out why and doing more of what works. IMO, as in Holland, cyclists would be a lot safer here if they rode every day regardless of whatever other changes occurred.

Khal said...

The Netherlands has a system where the motorist is presumed to be at fault. Its one of the things about the Vision Zero type philosophy that is somewhat over the edge.

http://bicycling.com/blogs/roadrights/2010/02/01/traffic-injustice-part-ii/

I prefer a system that neither presumes blame rests with the motorist nor whitewashes motorist behavior, but simply investigates in a fair and unbiased manner and calls a spade a spade.

Just as some motorists willfully speed, some cyclists willfully ride the wrong way or at night without lights. They need to take responsibility for the chaos they create.

Steve A said...

The Netherlands has a lot of cyclists that ride every day. Those are safer anywhere. Others quckly learn the local rules. Even if those others are tourists. That is indeed a numbers effect, but it has little to do with motorist behavior. I'm with Khal in wanting a fair system. Simply blaming motorists for everything is as much of a chump's game as accepting at face value the story of the motorist that drifts off the road and hits a pedestrian on the sidewalk.

Khal said...

After a week cycling in the Netherlands during grad school, I hopped a ferry to the UK and started riding from Great Yarmouth to Cambridge University. Riding through a rather huge roundabout heading out of town, I quite quickly noticed I was swimming salmon. A couple motorists dodged me as I dodged them and then one Brit in a small open-topped sports car quipped to me in a friendly manner "That's OK, Yank, we'll get you next time". He correctly concluded that I was making a newbie mistake, not realizing that in the UK they drove on the "other" side of the road.

Being a major road there was plenty of traffic on it for me to observe as a newly arrived cycling tourist. I had just not gotten my bearings yet and should have taken a few more minutes to compose myself before starting out. My boo-boo...

Steve A said...

I have the same problem. Luckily, it has always been while reading Franklin's "Cyclecraft."

Ham said...

I confess I haven't read the entire comment thread, but surely, there is a much easier explanation, which is very rarely spoken.

That is, there is an assumption that there are cyclists and drivers, two separate species. Whereas, in fact, they are one and the same. As a result, I believe there are more factors at work here. Extra cyclists don't come from nowhere, they are drivers too. That's not to say that all of a sudden all drivers are cyclists as well but some will be. In addition, those drivers who DO take more care influence the other drivers positively, in the same way as more law abiding cyclists influence the RLJ/pavement riding cyclists so that behaviour becomes the norm. I know that when I drive and give a cyclist decent room, the next driver follows the same line.

So, there is more that SIN than just the positive effect of more riders on the road.

Steve A said...

I know I've at least influenced my spouse and kids.

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